Reflectivity and Differential Reflectivity Rainfall Algorithm Performance at X-band

X-band weather radar systems present several advantages mainly related to their lower cost and smaller size relative to their S and C band counterparts. The main drawback of X-band is the attenuation suffered by the electromagnetic wave propagating through precipitation that reduces the reliability of rainfall estimates based on power measurements. Developments in dual-polarization techniques have provided solutions to mitigate this problem and have revived the interest on X-band radar systems for operational applications. Because of this growing interest, there is a need to evaluate the performance of X-band polarimetric radars for quantitative rainfall estimation. At X-band, attenuation affects any radar parameter based on backscatter power measurements such as Z_h, while differential attenuation affects parameters based on differential power measurement such as Z_dr. Consequently, Z_h and Z_dr must be corrected prior to use in quantitative applications such as rainfall estimation. However, correction procedures can introduce additional errors that impact on rain estimation and therefore must be applied with caution. When using the X-band rain algorithm based on Z_h and Z_dr, the biases due to attenuation and differential attenuation nearly cancel each other and result in a small bias of the estimated rainfall rate, so that correction of Z_h and Z_dr may not be needed. This paper investigates this property of rain rainfall estimation based on X-band dual-polarization measurements.